1. Field of the Invention
The present invention relates generally to fastening devices for joining structural members, and more specifically to mortise and tenon joint constructions in furniture manufacture.
2. Description of the Related Art
In the art of wooden furniture making, the dovetail joint is one of the most popular and secure mortise and tenon-type joints. However, it requires great care in preparation, as there is a significant incidence of product failure due to splitting wood and other such material faults. Further, any imprecision in the cutting or assembly of the mortise groove and tenon of a dovetail joint can affect the geometry of the furniture piece.
The precision problem is best illustrated in the context of one common method of constructing a drawer, wherein vertically-oriented mortise grooves are cut into the inner face of the drawer front, near its left and right side ends. These mortise grooves slidingly receive dovetail-shaped forward ends of the drawer""s left and right side panels. That is, the entire forward edge of each drawer side panel, from top to bottom, is shaped as a mating dovetail tenon. Thus, in horizontal cross-section, each tenon is essentially an isosceles trapezoid projecting, at its shorter base, from the end edge of a drawer side panel. And, each receiving mortise groove has a complementary shape.
This sliding dovetail joint, if manufactured with sufficient precision, is very easy to assemble, and it results in a tight, strong, durable, aesthetically-acceptable product. It is for these reasons that furniture manufacturers are very attracted to this type of drawer construction. It is for these same reasons that manufacturers of furniture designed to be user-assembled, called xe2x80x9cRTAxe2x80x9d (ready-to-assemble) furniture, have long sought a workable dovetail joint for use in their furniture kits. However, variations in the depth of the mortise cut, caused by differences in thickness among individual pieces of drawer-front panel stock, provoke continual problems with the mortise and tenon fit. For example, using the outer face of the drawer-front panel as the reference surface, if a thicker than usual piece of stock is run through a router to cut the mortise grooves, the grooves will be deeper than usual. Conversely, thinner pieces of stock will end up having shallower mortise grooves. It is not unusual for drawer-front stock to vary up to {fraction (1/16)} of an inch in thickness, causing a corresponding variation in mortise groove depth. This results in some mortise grooves grasping the more standardly-shaped tenons differently than others. This, in turn, results occasionally in loose joints and out-of-square construction. In custom furniture manufacturing, these problems can be cured by planing each piece of panel stock to the exact same thickness, or by making a custom-shaped tenon for each joint. However, RTA furniture makers do not have the luxury of taking that time. Thus, defective parts result. If not caught and discarded at the factory causing an immediate loss of revenue, these end up in the hands of end-users, breeding customer dissatisfaction. It is for these reasons the RTA furniture industry has yet to be able to enjoy the benefits of dovetail joinery.
Thus, it appears that some inexpensive, reliable means for forming a precise, durable sliding dovetail joint is needed. And, it would be especially beneficial if such a dovetail joint could be easily incorporated into RTA furniture constructions.
The modular dovetail joint of the present invention is adapted to overcome the above-noted shortcomings and to fulfill the stated needs. In its broadest sense, the invention is a joint bracket comprising: means for securely engaging an area adjacent an edge of a first structural member; and, means adapted for engaging a mortise groove in a second structural member, wherein the mortise groove-engaging means is integral with the first structural member""s edge-adjacent area engaging means. More specifically, the joint bracket of the invention comprises: a planar first flange; a planar second flange integral with, and disposed at less than a 180-degree angle to, the first flange; and, a tenon projecting from an outer surface of the second flange.
It is an object of the present invention to provide means for permitting RTA furniture manufacturers to get the benefits of using sliding dovetail joint construction, without the problems of material failure and imprecision which arise in using standard techniques.
It is a further object of the present invention to provide a joint structure for user-assembled furniture which is easy to assemble, yet as tight, strong, precise and secure as a custom-made dovetail joint.
Yet another object of the invention is to provide means for providing RTA furniture able to be shipped flat, and to be assembled with a mere screwdriver by an unskilled end user.
Still further objects of the inventive modular dovetail joint disclosed herein will be apparent from the drawings and following detailed description thereof.